scholarly journals Injection of Oort Cloud comets: the fundamental role of stellar perturbations

2008 ◽  
Vol 102 (1-3) ◽  
pp. 111-132 ◽  
Author(s):  
Hans Rickman ◽  
Marc Fouchard ◽  
Christiane Froeschlé ◽  
Giovanni B. Valsecchi
Keyword(s):  
Oort Cloud ◽  
Stellar Perturbations

scholarly journals Dynamical evolution of Oort cloud comets to near-Earth space

2006 ◽  
Vol 2 (S236) ◽  
pp. 43-54 ◽  
Author(s):  
Olga A. Mazeeva
Keyword(s):  
Dynamical Evolution ◽  
Absolute Magnitude ◽  
Oort Cloud ◽  
Outer Solar System ◽  
Earth Space ◽  
Near Earth Space ◽  
Long Period ◽  
Order Of Magnitude ◽  
Orbital Periods ◽  
Stellar Perturbations

AbstractThe dynamical evolution of 2⋅105 hypothetical Oort cloud comets by the action of planetary, galactic and stellar perturbations during 2⋅109 years is studied numerically. The evolution of comet orbits from the outer (104 AU <a<5⋅104 AU, a is semimajor axes) and the inner Oort cloud (5⋅103 AU <a<104 AU) to near-Earth space is investigated separately. The distribution of the perihelion (q) passage frequency in the planetary region is obtained calculating the numbers of comets in every interval of Δ q per year. The flux of long-period (LP) comets (orbital periods P>200 yr) with perihelion distances q<1.5 AU brighter than visual absolute magnitude H10=7 is ∼ 1.5 comets per year, and ∼18 comets with H10<10.9. The ratio of all LP comets with q<1.5 AU to ‘new’ comets is ∼5. The frequency of passages of LP comets from the inner Oort cloud through region q<1.5 AU is ∼3.5⋅10−13 yr−1, that is roughly one order of magnitude less than frequency of passages of LP comets from the outer cloud (∼5.28⋅10−12 yr−1). We show that the flux of ‘new’ comets with 15<q<31 AU is higher than with q<15 AU, by a factor ∼1.7 for comets from the outer Oort cloud and, by a factor ∼7 for comets from the inner cloud. The perihelia of comets from the outer cloud previously passed through the planetary region are predominated in the Saturn-Uranus region. The majority of inner cloud comets come in the outer solar system (q>15 AU), and a small fraction (∼0.01) of them can reach orbits with q<1.5 AU. The frequency of transfer of comets from the inner cloud (a<104 AU) to the outer Oort cloud (a>104 AU), from where they are injected to the region q<1.5 AU, is ∼6⋅10−14 yr−1.

scholarly journals Non-gravitational effects change the original 1/a-distribution of near-parabolic comets

2020 ◽  
Vol 633 ◽  
pp. A80 ◽  
Author(s):  
Małgorzata Królikowska
Keyword(s):  
Semimajor Axis ◽  
Oort Cloud ◽  
Gravitational Acceleration ◽  
Gravitational Effects ◽  
Long Period ◽  
Dynamical Properties ◽  
The Individual ◽  
Almost All ◽  
Data Processing Methods

Context. The original 1∕a-distribution is the only observational basis for the origin of long-period comets (LPCs) and the dynamical properties of the Oort Cloud. Although they are very subtle in the motion of these comets, non-gravitational effects can cause major changes in the original semimajor axis, 1∕aori. Aims. We obtained reliable non-gravitational orbits for as many LPCs with small perihelion distances of q < 3.1 au as possible, and determined the corresponding shape of the Oort spike. Methods. We determined the osculating orbits of each comet using several data-processing methods, and selected the preferred orbit using a few specific criteria. The distribution of 1∕aori for the whole comet sample was constructed using the individual Gaussian distribution we obtained for the preferred solution of each comet. Results. The derived distribution of 1∕aori for almost all known small-perihelion Oort spike comets was based on 64% of the non-gravitational orbits. This was compared with the distribution based on purely gravitational orbits, as well as with 1∕aori constructed earlier for LPCs with q > 3.1 au. We present a statistical analysis of the magnitudes of the non-gravitational acceleration for about 100 LPCs. Conclusions. The 1∕aori-distribution, which is based mainly on the non-gravitational orbits of small-perihelion Oort spike comets, is shifted by about 10 × 10−6 au−1 to higher values of 1∕aori compared with the distribution that is obtained when the non-gravitational effects on comet motion are ignored. We show the differences in the 1∕aori-distributions between LPCs with q < 3.1 au and those with q > 3.1 au. These findings indicate the important role of non-gravitational acceleration in the motion and origin of LPCs and in the formation of the Oort Cloud.

scholarly journals 3. An Alternate Interpretation of the Oort Cloud of Comets?

1977 ◽  
Vol 39 ◽  
pp. 93-97
Author(s):  
L. Kresak
Keyword(s):  
Relative Size ◽  
Oort Cloud ◽  
Observational Evidence ◽  
The Sun ◽  
First Passage ◽  
Radiation Mechanism ◽  
Original Surface ◽  
Significant Difference ◽  
First Time ◽  
Stellar Perturbations

Some problems of the current interpretation of the Oort Cloud are discussed. If observational selection is taken into account, no significant difference in physical characteristics of old and new comets is apparent, in spite of the required change in the radiation mechanism after the first passage near the Sun. The abundance of new comets puts special requirements on the relative size of the perihelion distances at which they lose their orbital characteristics and original surface properties, respectively. Stellar perturbations do not seem to be effective enough to displace the perihelia of new comets in a single revolution from the zone of insignificant planetary perturbations into the zone of detectability. Therefore, many physically new comets should appear as dynamically old, which is at variance with observational evidence. It is speculated whether the Oort Cloud really represents a reservoir of comets passing near the Sun for the first time or, alternatively, a region where the capability of building up extensive comas is being restored within periods of the order of 106 to 107 years.

scholarly journals The key role of massive stars in Oort cloud comet dynamics

Icarus ◽  
2011 ◽  
Vol 214 (1) ◽  
pp. 334-347 ◽  
Author(s):  
M. Fouchard ◽  
Ch. Froeschlé ◽  
H. Rickman ◽  
G.B. Valsecchi
Keyword(s):  
Massive Stars ◽  
Oort Cloud

scholarly journals Interstellar planets

2021 ◽  
Author(s):  
G. N. Dryomova ◽  
◽  
V. V. Dryomov ◽  
A. V. Tutukov ◽  
◽  
...  
Keyword(s):  
Planetary Systems ◽  
Oort Cloud ◽  
Gravitational Scattering ◽  
Parent Star

The lecture is devoted to the study of the role of gravitational scattering in the evolution of planetary systems. This mechanism explains the origin of the Oort cloud and free asteroids, comets, and planets (ACPs) from the parent star.

scholarly journals 2. Initial Energy and Perihelion Distributions of Oort-Cloud Comets

1977 ◽  
Vol 39 ◽  
pp. 87-91 ◽  
Author(s):  
P. R. Weissman
Keyword(s):  
Monte Carlo ◽  
Narrow Range ◽  
Monte Carlo Model ◽  
Initial Energy ◽  
Oort Cloud ◽  
Perihelion Distance ◽  
Initial States ◽  
First Time ◽  
Stellar Perturbations

A Monte Carlo model of stellar perturbations of the Oort cloud is used to study the distributions in energy and perihelion of comets entering the planetary region for the first time. The model is run for a variety of initial states and a range of velocity perturbations. In all cases the resulting orbits are uniformly distributed in perihelion distance in the planetary region, q < 20 AU. Most orbits are confined to a fairly narrow range in 1/a and hyperbolic orbits are rare.

scholarly journals Dynamical Evolution of Trans-Neptunian Objects in High-Eccentricity Orbits

2002 ◽  
Vol 12 ◽  
pp. 223-224
Author(s):  
V.V. Emel’yanenko
Keyword(s):  
Solar System ◽  
Inner Core ◽  
Dynamical Evolution ◽  
Oort Cloud ◽  
High Eccentricity ◽  
Parabolic Orbits ◽  
Stellar Perturbations

AbstractThe evolution of near-parabolic orbits with perihelia in the trans-neptunian region has been studied, considering the action of planetary, Galactic and stellar perturbations for the age of the Solar System. This investigation has led to the conclusion that the observed trans-neptunian objects in high-eccentricity orbits might originate from the inner core of the Oort cloud.

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